Improvement in dye sensitized solar cells from past to present

Several emerging renewable technologies are available to satisfy the current energy demand and to minimize the effect of environmental degradation caused by high consumption of fossil fuels. These technologies are not mature enough to solve this problem but require more time for improving the efficiency, and cost reduction to become the economical alternative of fossil fuels. In this paper Dye-sensitized solar cell (DSSC) has been discussed in detail owing to advancement in the technology. Since each component of DSSC is responsible for a specific function, therefore, comprehensive literature studies has been done on individual section to understand the technology in depth. All the advancement in sensitizer, semiconductors, electrolyte, electrodes, additives, sealing and anchoring groups are included in this review with performance parameter of DSSC. Focus of this article is to provide summary of all available literature since beginning to date.     

A new family of four-ring bent-core nematic liquid crystals with a highly polar end-group

A new family of four-ring achiral bent-core compounds derived from 2-methyl 3-amino benzoic acid with the methyl group in the bent direction incorporated into the central core have been designed and synthesised. These compounds possess an alkoxy chain attached at only one end of the bent core molecule, while the other arm consists of a biphenyl moiety possessing a highly polar cyano-group. The molecular structure has been confirmed by elemental analysis and spectroscopic data, and the thermal behaviour and phase characterisation has been investigated by differential scanning calorimetry and polarising microscopy. All the compounds exhibit a wide-range enantiotropic nematic phase. A comparison with non-mesomorphic unsubstituted and 4-methyl-substituted homologues is also presented.     

Dendritic Polyglycerol‐Derived Nano‐Architectures as Delivery Platforms of Gemcitabine for Pancreatic Cancer

Dendritic polyglycerol‐co‐polycaprolactone (PG‐co‐PCL)‐derived block copolymers are synthesized and explored as nanoscale drug delivery platforms for a chemotherapeutic agent, gemcitabine (GEM), which is the cornerstone of therapy for pancreatic ductal adenocarcinoma (PDAC). Current treatment strategies with GEM result in suboptimal therapeutic outcome owing to microenvironmental resistance and rapid metabolic degradation of GEM. To address these challenges, physicochemical and cell‐biological properties of both covalently conjugated and non‐covalently stabilized variants of GEM‐containing PG‐co‐PCL architectures have been evaluated. Self‐assembly behavior, drug loading and release capacity, cytotoxicity, and cellular uptake properties of these constructs in monolayer and in spheroid cultures of PDAC cells are investigated. To realize the covalently conjugated carrier systems, GEM, in conjunction with a tertiary amine, is attached to the polycarbonate block grafted from the PG‐co‐PCL core. It is observed that pH‐dependent ionization properties of these amine side‐chains direct the formation of self‐assembly of block copolymers in the form of nanoparticles. For non‐covalent encapsulation, a facile “solvent‐shifting” technique is adopted. Fabrication techniques are found to control colloidal and cellular properties of GEM‐loaded nanoconstructs. The feasibility and potential of these newly developed architectures for designing carrier systems for GEM to achieve augmented prognosis for pancreatic cancer are reported.     

Compound A Increases Cell Infiltration in Target Organs of Acute Graft-versus-Host Disease (aGVHD) in a Mouse Model

Systemic steroids are used to treat acute graft-versus-host disease (aGVHD) caused by allogenic bone marrow transplantation (allo-BMT); however, their prolonged use results in complications. Hence, new agents for treating aGVHD are required. Recently, a new compound A (CpdA), with anti-inflammatory activity and reduced side effects compared to steroids, has been identified. Here, we aimed to determine whether CpdA can improve the outcome of aGVHD when administered after transplantation in a mouse model (C57BL/6 in B6D2F1). After conditioning with 9Gy total body irradiation, mice were infused with bone marrow (BM) cells and splenocytes from either syngeneic (B6D2F1) or allogeneic (C57BL/6) donors. The animals were subsequently treated (3 days/week) with 7.5 mg/kg CpdA from day +15 to day +28; the controls received 0.9% NaCl. Thereafter, the incidence and severity of aGVHD in aGVHD target organs were analyzed. Survival and clinical scores did not differ significantly; however, CpdA-treated animals showed high cell infiltration in the target organs. In bulk mixed lymphocyte reactions, CpdA treatment reduced the cell proliferation and expression of inflammatory cytokines and chemokines compared to controls, whereas levels of TNF, IL-23, chemokines, and chemokine receptors increased. CpdA significantly reduced proliferation in vitro but increased T cell infiltration in target organs.     

Receptor binding affinity based comparative QSAR study of testosterone derivatives

The quantitative structure activity relationship models of 22 testosterone derivatives have been made with the help of topological and quantum chemical parameters. The molecular modeling and geometry optimization have been carried out with CAChe Pro software. The calculations of topological and quantum chemical parameters have been done by MOPAC 2007. The statistical parameters are calculated by STATISTICA and SSP software. The study indicates that the topological parameters better predict the receptor binding affinity of testosterone derivatives, whereas quantum chemical parameters better predict androgenic potency of testosterone derivatives as indicated by correlation coefficient, standard error, standard error of estimation, p value, t value, and degree of freedom of the quantitative structure activity relationship (QSAR) models. The predicted activity values obtained by these QSAR models are close to observed activity. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012     

Amide linkage in novel three-ring bent-core molecular assemblies: polar mesophases and importance of H-bonding

Here, we report the first examples of achiral unsymmetrical three-ring bent-shaped liquid crystals comprising amide and imine linkages with transverse substituents of methyl and chloro moieties on the central phenyl ring in the core, exhibiting polar banana phases. The extensive intra and inter molecular H-bonding induced novel banana mesomorphic phases. One-dimensional stacking in the mesomorphic phase as well as ferroelectric polar order promoted by intermolecular H-bonding of amide linkage is demonstrated. The compounds exhibit multifunctional properties viz., the enantiotropic liquid crystalline (LC) phase at ambient temperatures, electro-optical response, spontaneous polarisation, emission characteristics with large Stokes shift, and even charge distribution with large voltage holding ratio (VHR) values. The smectic type phase was confirmed by XRD studies and polar order was established by switching current and dielectric investigations. DFT studies revealed the importance of their suitability for display applications.     

Single sample extraction protocol for the quantification of NAD and NADH redox states in Saccharomyces cerevisiae

A robust redox extraction protocol for quantitative and reproducible metabolite isolation and recovery has been developed for simultaneous measurement of nicotinamide adenine dinucleotide (NAD) and its reduced form, NADH, from Saccharomyces cerevisiae. Following culture in liquid media, yeast cells were harvested by centrifugation and then lysed under nonoxidizing conditions by bead blasting in ice-cold, nitrogen-saturated 50 mM ammonium acetate. To enable protein denaturation, ice cold nitrogen-saturated CH(3)CN/50 mM ammonium acetate (3:1 v/v) was added to the cell lysates. Chloroform extractions were performed on supernatants to remove organic solvent. Samples were lyophilized and resuspended in 50 mM ammonium acetate. NAD and NADH were separated by HPLC and quantified using UV-Vis absorbance detection. NAD and NADH levels were evaluated in yeast grown under normal (2% glucose) and calorie restricted (0.5% glucose) conditions. Results demonstrate that it is possible to perform a single preparation to reliably and robustly quantitate both NAD and NADH contents in the same sample. Robustness of the protocol suggests it will be (i) applicable to quantification of these metabolites in other cell cultures; and (ii) amenable to isotope labeling strategies to determine the relative contribution of specific metabolic pathways to total NAD and NADH levels in cell cultures.     

Enzyme Instructed Self‐assembly of Naphthalimide‐dipeptide: Spontaneous Transformation from Nanosphere to Nanotubular Structures that Induces Hydrogelation

Understanding the structure‐morphology relationships of self‐assembled nanostructures is crucial for developing materials with the desired chemical and biological functions. Here, phosphate‐based naphthalimide (NI) derivatives have been developed for the first time to study the enzyme‐instructed self‐assembly process. Self‐assembly of simple amino acid derivative NI‐Yp resulted in non‐specific amorphous aggregates in the presence of alkaline phosphatase enzyme. On the other hand, NI‐FYp dipeptide forms spherical nanoparticles under aqueous conditions which slowly transformed into partially unzipped nanotubular structures during the enzymatic catalytic process through multiple stages which subsequently resulted in hydrogelation. The self‐assembly is driven by the formation of β‐sheet type structures stabilized by offset aromatic stacking of NI core and hydrogen bonding interactions which is confirmed with PXRD, Congo‐red staining and molecular mechanical calculations. We propose a mechanism for the self‐assembly process based on TEM and spectroscopic data. The nanotubular structures of NI‐FYp precursor exhibited higher cytotoxicity to human breast cancer cells and human cervical cancer cells when compared to the nanofiber structures of the similar Fmoc‐derivative. Overall this study provides a new understanding of the supramolecular self‐assembly of small‐molecular‐weight hydrogelators.     

Controlled release of DNA from photoresponsive hyperbranched polyglycerols with oligoamine shells

Two photo-responsive core/shell nanoparticles based on hyperbranched polyglycerol (hPG) are synthesized for controlled release of DNA. The shell is composed either of bis-(3-aminopropyl)methylamine (AMPA) or pentaethylenehexamine (PEHA) derivatives and is attached to the hPG core with a photo-responsive o-nitrobenzyl linker. Ethidium bromide displacement assay, gel electrophoresis, DLS, and ζ-potential measurements are performed with these nanoparticles. Photo-responsive changes within the carrier scaffold are investigated by irradiating the polymer solution with 350 nm monochromatic light. Fully covered APMA-shelled carriers are found to complex the DNA at an N/P ratio of 10 with an average size ranging from 54 to 78 nm depending on the degree of functionalization of the core.